As I write this in the summer of 2023, headlines are awash with reports questioning the efficacy of the MIND diet and, by extension, casting doubt on the benefits of all plant-centered diets. A study titled Trial of the MIND Diet for Prevention of Cognitive Decline in Older Persons, which sparked much of the discourse, provides a nuanced perspective, offering a comprehensive exploration of the potential cognitive benefits of the MIND diet.
Definition
What does ‘MIND’ diet stand for?
The ‘MIND’ in ‘MIND diet’ is a nested acronym. The ‘MIND’ stands for ‘Mediterranean-DASH Intervention for Neurodegenerative Delay’. The ‘DASH’ stands for ‘Dietary Approaches to Stop Hypertension’.
The MIND diet is a unique fusion of the Mediterranean diet and the DASH diet. Both of these diets have been widely studied and associated with numerous health benefits, including potential protective effects against cognitive decline.
The Mediterranean diet — rich in fruits, vegetables, whole grains, and healthy fats — has been linked to lower rates of heart disease, and has been suggested to improve longevity.
The DASH diet, designed to combat hypertension, emphasizes low sodium intake and promotes a variety of nutrient-rich foods.
The MIND diet takes elements from both these diets but specifically includes foods and nutrients that medical literature and data have shown to be good for brain health.
Martha Clare Morris, a nutritional epidemiologist at Rush University Medical Center, developed the MIND diet based on information that has linked certain foods with better cognitive function and reduced risk of dementia.
Who created the MIND diet?
Martha Clare Morris, a nutritional epidemiologist at Rush University Medical Center, developed the MIND diet based on information that has linked certain foods with better cognitive function and reduced risk of dementia.
Is the MIND diet backed by science?
Numerous studies and reviews have confirmed the benefits of the MIND diet. A study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association found that the MIND diet lowered the risk of Alzheimer’s by as much as 53% in participants who adhered to the diet rigorously, and by about 35% in those who followed it moderately well.
Another study in the Journal of the American Geriatrics Society discovered that adherence to the MIND diet is associated with better cognitive performance, specifically in memory and executive function.
Despite recent reports, the body of evidence supporting the benefits of the MIND diet and other plant-centered diets is substantial. It’s essential to consider the full breadth of research and understand that dietary impact on health is a complex interplay of many factors, including genetics, lifestyle, and overall nutritional intake.
The trial which supports the MIND diet, explained
The study I mentioned at the start of this article — the Trial of the MIND Diet for Prevention of Cognitive Decline in Older Persons — was conducted across two sites, and utilized a randomized, controlled trial design.
The participants were older adults who were cognitively unimpaired but had a family history of dementia, a body-mass index (BMI) greater than 25, and a diet that was deemed suboptimal. These criteria were chosen to target a population that might be at a higher risk of cognitive decline and could potentially benefit the most from dietary intervention.
Participants were randomly assigned to follow either the MIND diet with mild caloric restriction or a control diet with mild caloric restriction for a period of three years.
To support adherence to the assigned diets and to promote weight loss, all participants received counseling. This comprehensive approach was designed to ensure that any observed effects could be attributed to the diet itself, rather than other lifestyle factors.
The main goal of the study was to measure how much the scores for overall thinking ability and four specific areas of thinking changed from the beginning of the study.
These scores were derived from a comprehensive series of 12 tests, providing a robust measure of cognitive function.
The secondary outcome was the change in MRI-derived measures of brain characteristics in a nonrandom sample of participants.
This allowed the researchers to investigate potential changes in brain structure that might be associated with the diets.
The results of the study showed that both groups experienced improvements in global cognition scores from their starting points to the third year.
The MIND diet group saw increases of 0.205 standardized units, while the control-diet group saw increases of 0.170 standardized units.
However, the difference between the two groups was not statistically significant, suggesting that both diets may have similar effects on cognitive function.
In addition to cognitive scores, the study also examined changes in brain structure. The results showed that changes in white-matter hyperintensities, hippocampal volumes, and total gray- and white-matter volumes on MRI were similar in the two groups. This suggests that neither diet had a significant impact on these measures of brain structure over the 3-year period.
Ultimately, the study found that among cognitively unimpaired participants with a family history of dementia, changes in cognition and brain MRI outcomes from baseline to year three did not differ significantly between those who followed the MIND diet and those who followed the control diet with mild caloric restriction.
This suggests that both diets may have potential benefits for cognitive function, but further research is needed to fully understand these effects and their implications for dementia prevention.
What are the limitations of the study?
The limitations of the study are noteworthy, and warrant further discussion.
Power of the Study: the study might not have had enough statistical power to detect a significant difference between the two groups. This is because both groups improved over the course of the study. In other words, the study might not have had a large enough sample size or duration to detect a small but potentially meaningful difference between the MIND diet and the control diet.
Initial Conditions of the Control Group: the control group started at a higher level of cognitive function, which could have influenced the results. If the control group had a higher baseline cognitive function, it might have been harder for them to show significant improvement compared to the MIND diet group. This could have biased the results towards a null effect.
Weak Intervention and Adherence Measures: the MIND diet intervention and adherence measures were reportedly weak. This means that it might have been difficult for participants to accurately and consistently follow the diet, which could have diluted any potential effects of the diet on cognitive function. Furthermore, the study did not appear to have a robust method for verifying adherence to the diet, which could further confound the results.
Impact of COVID-19 Pandemic: another potential confounding factor is the timing of the study, which coincided with the COVID-19 pandemic. The stress and lifestyle changes associated with the pandemic could have independently affected cognitive function, irrespective of diet. This is suggested by the observation that both groups were improving until around 2020, when both groups started to decline. This pattern suggests that external factors, such as the pandemic, might have influenced the results.
So, while the study provides valuable data on the potential cognitive benefits of the MIND diet, these limitations suggest that the results should be interpreted with caution. Further research is needed to confirm these findings and to better understand the potential role of diet in cognitive function and dementia prevention.
References
Morris MC, Tangney CC, Wang Y, Sacks FM, Bennett DA, Aggarwal NT. MIND diet associated with reduced incidence of Alzheimer’s disease.
Berendsen AAM, Kang JH, van de Rest O, Feskens EJM, de Groot LCPGM, Grodstein F. The Dietary Approaches to Stop Hypertension Diet, Cognitive Function, and Cognitive Decline in American Older Women.
About The Author
Dean Sherzai, MD, PhD
Dr. Dean Sherzai is co-director of the Alzheimer’s Prevention Program at Loma Linda University. Dean trained in Neurology at Georgetown University School of Medicine, and completed fellowships in neurodegenerative diseases and dementia at the National Institutes of Health and UC San Diego. He also holds a PhD in Healthcare Leadership with a focus on community health from Andrews University.
Get more brain science direct to your email inbox
Sign up for the Brain Docs newsletter for weekly recipes, brain teasers, neuroscience facts, podcast updates, and more — for free!
